This is neither the high magic of Faerun, or the common magic-as-technology of eberron. Most higher level casters who got involved in the war became targets to assassins and enemy casters. So lower-level magic is generally practiced on the battlefield, if at all, with more practiced and educated wizards staying away from enemy crosshairs. Higher level practicioners are rare because of the mortality associated with the study now, and those who do exist generally tend to keep to themselves, or occupy higher governmental or academic posts.
High Magic in this world requires a focus of some sort. That is, in order to perform acts of great magic like levitating mountains or enchanting cities, the magician must work his magics through a near-scientific discipline. This takes many forms based on the desired effects. The gnomes pioneered Gem Magic, which makes employing personal abjurations, transmutations and divinations easier and more powerful; they might imbue a crown's center ruby with a number of abjurations which make assassination near-impossible. The dwarves invented rune magic, primarily used for powerful weapon and armor enchanting. The halflings have their own form of shamanism, and have recently come to use menhirs to use as focal points for areas of magical effects. The methods by which these effects are achieved are as varied as the effects themselves, but the fact remains that they can not exist without some sort of mathematical application and their focus, which are usually very closely guarded secrets. As such, epic magic should only be achieved by a wizard or sorcerer who takes levels in a prestige class devoted to that discipline, I will develop a 3.5ed example of one as time goes on.
Sorcery must have a source as well, though the sorcerer need not know the source of his powers himself. Fiendish or draconic blood, or even being born in an area with an affinity for a plane, or lingering arcane or divine magic, can all cause it. The sources of sorcerous power are numerous, but there must be a source for it, it does not just happen spontaneously. Pathfinder has some excellent rules for sorcerers which I based this on.

Types of High Magic

There are many types of high magic, but all of these require significant study and precision. There is nothing saying that Eladrin Geometric Magic could not be mixed with Gnome Gem Magic to make an incredibly powerful transmutation circle; however, the conflicting energies and precise nature of high magic means that this practice would be amazingly dangerous, like trying to mash a nuclear power plant into a Rocketship. If there was a small error in the pattern, or a flaw in one of the stones used, while that may have been acceptable in order to create the original effect, in the mixing of the two kinds it could be catastrophic. As such, this practice of mixing high magics is almost never undertaken, with only a few notable public examples; one of which is the recent capture of the Tarrasque, and even that required the partial sacrifice of a god to smooth it along.

Xalli Geometric Magic - Uses drawn patterns with focus nodes of power, some not even occupying the same planes of existence, to create transmutation or conjuration circles. Large scale examples include menhir circles, planted redwood forests, and some whispers say that even the very layout of the Eladrin cities are a large scale hidden Eladrin circle.

Dwarven Rune Magic - This can be most easily related to computer code, a very precise set of instructions to the universe, written in a language it can understand. Rune magic works by being written on the surface of the object it is to affect. Runes are an ancient language, and very precise in their construction and their resulting runeword compositions. It's a very important distinction, for example, between "Turn this arm to stone" and "Turn this arm to living stone." One of the most famous practitioners of Rune Magic is also it's patron, Ro, The Runed God. As legend has it, he discovered a way to turn himself into a god by inscribing a huge and complex set of runewords onto his skin, but no matter how he looked at it he simply did not have enough room on his body for the completed Runewords. His solution was to flense his own skin, one strip at a time, and complete the runewords on the other side. The combination of extreme pain, and frenzied devotion, drove him slightly mad, and so he represents the madness which a lust for arcane magic brings.

Gnome Gem Magic - A secret only the Gnomes have mastered, and one which they zealously protect from outsiders. Their gems are tiny vessels of might which have the advantage of being highly transportable and socketed in whatever they wish. Many battles, and even wars, have been fought over these powerful artifacts as small as a pebble.

Draconic Blood Magic - A combination of sacrifices, alchemy and breeding; like a cross between Animal Husbandry, Genetic Engineering and the Occult. It is said that most of the world's most terrible "mistake" creatures, Owlbears, Manticores, Chimera and so on, were born from uneducated dabblings in blood magicks. True educated practicioners in blood magic do nothing in a hasty manner, this was developed by a race which lives thousands of years after all. The dragons take advantage of the fact that they live for many generations, by supervising the slow interbreeding and genetic selection, with subtle alchemic and magical intervention, in order to meet their goals. Through this process several deviations from standard races were made, like the Duergar, Shifters, Changelings, and most obvious, the Dragonborn.

Giant Truename Magic - Also known as Lore Magic, and delves into Pact magic as well. Giants are a very egocentric race, believing that everything revolves around themselves, and as such place great importance on the self. It is from this that sprang the idea that by knowing everything about a person, particularly their true cosmic name, they could gain the best advantage, and with enough practice even magical compulsion. Some Giant wizards have gotten so strong that they could utter a few words and erase a being entirely from existence. The discovery of Truename magic incited a huge thirst for knowledge in Giant leaders and magic practicioners, but being slightly conspicious with their size they fell back on divinations and the use of spy-slaves, especially the Kenku, who were uniquely suited for the task. Truename magic is used for all manner of divinations, compulsions, and making deals with devils, gods, and even more bizarre manner of creature.

Note:Mekkfellow rely on clockwork and alchemy, a calling which has also been imported to the communist state of Ostivakia and adopted by the dwarves there.